1. Field of the Invention
The present invention relates to methods for extinguishing fire, preventing fire, and reducing or eliminating the flammability of a flammable working fluid using monobromoperfluoroketones, monohydromonobromoperfluoroketones, (perfluoroalkoxy)monobromoperfluoroketones, (fluoroalkoxy)monobromoperfluoroketones, and monochloromonobromoperfluoroketones.
2. Description of Related Art
Numerous agents and methods of fire fighting are known and can be selected for a particular fire, depending upon factors such as its size, location and the type of combustible materials involved. Halogenated hydrocarbon fire fighting agents have traditionally been utilized in flooding applications protecting fixed enclosures (e.g., computer rooms, storage vaults, telecommunications switching gear rooms, libraries, document archives, petroleum pipeline pumping stations, and the like), or in streaming applications requiring rapid extinguishing (e.g., military aircraft, commercial hand-held extinguishers). Such extinguishing agents are not only effective but, unlike water, also function as “clean extinguishing agents,” causing little, if any, damage to the enclosure or its contents.
The most commonly-used halogenated hydrocarbon extinguishing agents have been the bromine-containing compounds bromotrifluoromethane (CF3Br, Halon™1301) and bromochlorodifluoromethane (CF2ClBr, Halon™1211). These bromine-containing halocarbons are highly effective in extinguishing fires and can be dispensed either from portable streaming equipment or from an automatic room flooding system activated either manually or by some method of fire detection. However, these compounds have been linked to ozone depletion. The Montreal Protocol and its attendant amendments have mandated that Halon™1211 and 1301 production be discontinued.
Thus, there is a need in this field for methods using substitutes or replacements for the commonly-used, bromine-containing fire extinguishing agents. Such substitutes used in such methods should have a low ozone depletion potential; should have the ability to extinguish, control, and prevent fires, e.g., Class A (trash, wood, or paper), Class B (flammable liquids or greases), and/or Class C (electrical equipment) fires; and should be “clean extinguishing agents,” i.e., be electrically non-conducting, volatile or gaseous, and leave no residue upon use. Preferably, such substitutes used in such methods will also be low in toxicity, not form flammable mixtures in air, have acceptable thermal and chemical stability for use in extinguishing applications, and have short atmospheric lifetimes and low global warming potentials.
Various different fluorinated hydrocarbons have been suggested for use as fire fighting agents. For example, in U.S. Pat. No. 6,300,378, Tapscott discloses tropodegradeable bromine-containing halocarbon additives to decrease the flammability of refrigerants, foam blowing agents, solvents, aerosol propellants, and sterilants. In U.S. Pat. No. 6,478,979, Rivers et al. disclose the use of perfluorinated ketones in fire extinguishing.